Control switch



May 6, 1930. A. J. KERCHER 1,757,314

y coNTRoL swITGH Filed June 12, 1922 2 sheets-sheet 1 IllI lll I'l llllllllllllllllllx IIIII Illllll WWA/55s INVENTOR.

A TTORNEYS.

May 6, 193i). -A. J. KERCHER I 1,757,314

Y CONTROL SWITCH Filed June 12, 1922 2 sheets-sheet 2 Z4 $5 (f .2%. 4 6/ /2 vf 2 s.. 72

l 67- ,/v 4i412' 'L44 Z 3 IWIIIIIIIIIIIIII f3 e 5 /7 75 E WITNESS' n A INI/ENTORl A TTORNE YS Patented May 6, 1930 UNITED STATES ARTHUR J. KERGHER, or

CONTROL Application med June 12,

This invention relates t'o a switch adapted to control pressure or temperature, and more particularly to a switch that closes and opens an electric circuit in response to variations in temperature or gas pressure. Such a device may be useful for example for the control of room temperature, of the operation of refrig# erating apparatus, or of boiler pressure.

It is one of the objects of my invention to provide a control switch that is positive in its action, readily adjustable to take care of y varying conditions, and inexpensively manufactured. y,

It is desirous, in a control switch of the type mentioned, that the contacts operate at a defi@ nite temperature or pressure, and that after a substantial variation of the temperature or pressure from the critical value, the switch will be returned to its original positionf If no special provisions were taken to make the switch return to its original position only after a substantial variation from the critical temperature or pressure, there would be a likelihood of causing constant fluttering of the contacts. It is another object of m invention to provide a triggerlike and de nite action of the switch to open and close contacts at controllable separated 'values of temperature or pressure.

Still another object of my invention is to provide a simple and reliable control switch arranged to be operated in one direction by the volatilization of a liquid such as ethyl chloride or ethylbromide, and in the other direction'indirectly by the condensation of the liquid by the aid of electromagnets.

My invention possesses other advantages, some of which, with the foregoing, will be set forth at length in the following specification where I shall outline in full that form of the invention which I have selected for illustration in the drawings accompanying and` forming part of my present specification. In the drawings, I have shown but one embodiment of my invention, but it' is to be understood that I do not limit myself to that form, since the invention as expressed in the claims may be embodied in other forms as Well.

Referring to the drawings:

loted on the stationary member 14 between PATENT OFFICE I BERKELEY, CALIFORNIA SWITCH 1922. serial No. 567,876.

Figure 1 is a sectional view'of a complete switch, taken along line 1-1 of Fig. 2;

Fig. 2 is a front View of the switch;

Fig. 3 is a side view thereof; and v Fig. 4 is a wiring diagram illustrating one application of my invention.

In the present instance the switch is shown as having two main movable contact points 11, one of which is seen in Fig. 3. These movable points are circular in section,V and are arranged to coact with similar stationary posts12. The contacts 11 are carried one on each arm 13, pivoted to a stationary plate p 14. Eachl of the contacts 11 carries an integral stud 15 by means of which it is fastened to its arm 13. Appropriate insulating material such as washers 16 are provided so as not to ground the contacts 11 upon the arms 13. The movement of the arms 13 t-o separate the contacts depends on gravity, the ositon of the switch as actually installed eing such that this may be readily accomplished.

The movement of the switch to the closed position lis arranged to be effected by somel temporarily active agency, such as electromagnet-ism, For this purpose a pair of coils 17 are provided, having the usual cores and a connecting strap 18 between the cores of magnetic material. An armature 19 is pivthe arms 13, and is shaped, as shown in Figs.

1 and 2, so as to extend underneath the arms 1 3, Between these arms and the armature 19 resilient connections are provided, comprising bolts 2O fastened to the armature 19, a5 and extending through the arms 13, springs 21interposed between the heads of the bolts 2O and arms 13,.and washers 22 serving as '1 seats for the springs. When armature 19 is attracted by the electromagnets 17, there is a tendency to compress springs 21, and the i springs in turn tend to move the arms 13 so as to close the contacts. A pivoted latch 23 is arranged to hold the armature in its attracted position even after themagnets 17 are de-en- 95 ergized. The upper portion of armature 19 is undercut slightly to form a good engagement with the hook 24 of the latch 23, as shown most clear] in Fig. 1.

The operation o the contacts is performed, 1pc

ized gas is varied.

-as stated hereinbefore, by variations in pressure or temperature. In the present instance, the mechanical unlatching of the armature occurs when the pressure or temperature within a pressure cell reaches a definite value. This cell has a buckled diaphragm 26 forming one of its boundaries. The interior of the cell itself is adapted to be placed in communication with a container 27 by means of tubing 28. This container is placed in such a position that it is exposed to the temperature which it is desired to control, and in order that it may the more readily absorb or radiate heat, it is provided with corrugations as shown, Vand is made of a metal having high heat conductivity. Within the container 27 is a highly volatile` liquid 29, such as ethyl chloride gr ethyl bromide. The gas pressure within the cell 25 is equal to the pressure in the container 27, which in\turn is dependent upon the temperature of the liquid 29, and the position of diaphragm 26 is a function of this pressure. As this pressure is increased, the diaphragm 26 is urged outwardly, against the tension of a spring 30. This spring tends to move a piston orrplunger 31 toward the left, and is guided against the collar 32 by the rod 33. In order to provide a good contact surface between the diaphragm 26 and the head of plunger 31, a flexible circular member 34 is fastened, as by means of a member 35, to the head of the plunger. The cell 25, the plunger 31 and the spring 30 are housed in a pair of cast members 36 and 37, which also conveniently serve to support all of the other operating parts of the switch. These two parts are shown as held together by screws 38. The part 37 has an integral tubular extension 39 within which the spring 30 is dis posed. The compression of this spring may be adjusted to adjust the temperature of pressure at which the switch operates, and for this purpose the end of the extension 39 is threaded to receive a hollow thumb screw 40. By turning this screw, the spring is either allowed to expand or made to contract, and in this way the force urging the diaphragm against the pressure of the volatil- Thus the value` of the temperature necessary to force plunger 31 far enough to' operate the latch may be controlled. A washer 41 is interposed between the bottom of thumb screw and the top of spring 30 in order that an even bearing surface may be maintained between these two parts.

The movement of the plunger 31 outwardly in response to increasing gas pressure in the cell 25, if sufficiently prolonged, releases the latch 24 and permits the contacts to drop open. This is accomplished by the aid of the lever 42 pivoted to an ear 43, which is preferably cast integral with the part 37 This lever has an arm 44 extending through an aperture in the tubular extension 39, into a groove 45 between the plunger 31 and the collar 32, in such a way that this lever is oscillated when mthe plunger moves. The other arm 46` of the lever 42 is adapted to pushy against an adjustable screw 47 which is held in the pivoted latch 23. When this latch is lifted clear of the armature 19, the contacts 11 drop away from the contacts 12. A small compression spring 48 serves to keep the latch engaged until an appreciable force is exerted against the screw 47. The latch is most conveniently pivoted in an ear 49, also preferably cast integral with the member 37.

The mechanical support for the stationary contacts 12 includes posts 50 fastened to, but insulated from, a rib 51 which extends across the face of the casting 37, at the same plane as the top edge of the tubular portion 39. Through the post y 50 extend screws 52 to which the conductors leading to the contacts 12 may be fastened. The contact 12 is held lof member 37 and bosses 55 into the strap 18. At the front end of the magnets the stationary plate 14 passes around the tubular extension 39 and also the cores, and it is rigidly spaced from the strap 418 by the strut 56 which passes centrally between the two magnet coils. Thus a compact supporting structure is obtained for the magnets. 17, the cores, the armature 19 and the arms 13.

The armature 19 is provided with an oval aperture 57 so that the tubular extension 39 may pass therethrough. It also carries a weight 58 near itsfree end, so that a considerable momentum' may be imparted to the armature when it is attracted by the magnets 17 which momentum is useful in causing a positive engagement of the latch 24 with the armature. Without this additional momentum, the pull on the armature would cease as soon as the main contacts would engage, since they short-circuit the electromagnet, and before the hook becomes active. With .the weight, the momentum serves to carry the armature to its positive locking/position even after the electromagnets are deenergized. A bumper or stop 59 is carried conveniently upon the tubular extension 39, to limit the movement of the armature 19 away from the poles of the electromagnets 17. A pair of lugs 60 are cast integral with the member 37 to provide means for mounting a housing over the moving parts of the device.

An auxiliary electric heating element 61 is placed within the cell 25, and is provided vwith external terminals 62. This heating element is of relatively high resistance,` and becomes active upon the opening of the main contacts 11 and 12.

Various auxiliary control contacts are also made and broken during the operation of the switch. Thus the arm 46 of lever 42 carries an insulated movable contact 63 which cooperates with a stationary insulated contact 64. These contacts open when the lever 42 moves to trip the latch 24. The stationary contact 64 is electrically connected with a binding post 65 in a more accessible part of the device, to which one terminal of the electromagnets 17 is connected, as indicated in F1 g. 4. The control-of the auxiliary heating` elf ment 61 is eected by insulated contacts 66 and 67, carried respectively by the screw 47 and the lever 42, and open when/the main contacts are closed. The heating element 61 is adapted to be connected across a circuit of constant potential when contacts 66 and 67 engage. There is furthermore a connection 68 between the two movable contacts 11, so that these contacts are directly in series. Appropriate insulation, such as the glass beads 69, may be placed over the conductor 68 in order to prevent it grounding upon any metal part of the switch.

The various connections and the operation of the switch to control a regulating motor may be best understood from the wiring diagram of Fig. 4. The regulating motor 70 may bc used to control a gas valvefor a furnace,

`or the circulation of cooling medium, or to perform any other temperature or pressure regulating function. The connections for the motor 70 are normally completed in this instance, and are interrupted upon a rise in pressure or temperature above the required value. While the pressure or temperature is low, the lever 42 does not serve to disengage the latch hook 24, and the connections are as shown in the diagram. The motor 7'() has its circuit completed across mains 71 by wire 72, one ofthe stationary contacts 12, through a movable contact 11, connection 68, through the other contacts 11 and 12 and connections 73 and 74 back to the main 71. The electromagnets 17 are bridged across the main contacts 11 and 12, by conductor 75, connector 65, and contacts 63 and 64. Thus these electromagnets are short circuited and do not exertsany pull upon the armature 19, which is held in position solely by the latch. As soon as the pressure in cell 25 becomes great enough, the lever 42 lifts the latch 23 and the armature 19 is released. At the same time, contacts 63 and 64 are opened, so that the magnets 17 remain de-energized. The circuit for the motor 70 is now open. vIf no further provisions were made, the opening of the motor circuit would in a very short time cause a slight reduction in pressure in cell 25, causing a reverse movement of diaphragm 26, and

contacts 63 and 64 would close. T his would the main contacts open, the circuitfor the auxiliary heating element 61 is completed,

through connections 7 6 and 77. The eii'ect is a tendency to increase the pressure slightly in cell 25, even after the motor circuit is interrupted. Thus the diaphragm 26 cannot move back to a position where contacts`63 and 64 are connected, until the tendency to decrease the pressure due to the interruption of the motor circuit, overcomes the tendency to increase the pressure due to the completion of the circuit for the auxiliary heating element. The auxiliary heater may beso proportioned that the electromganets 17 remain inactive until the temperature of the container 27 is below the crit-ical value by any appreciable amount. As soon as this occurs, the circuit for electromagnets 17 is completed at contacts 63 and 64; the armature is attracted and the magnetsenergized until contacts 11 and 12 are made, short-circuiting these electromagnets. However, the momentum imparted to the armature 19, due to the weight 58, is suficient to cause the. armature to travel far enough to cause its engagement by the latch hook 24. At the same time the circuit for the at contacts 66 and 67', and the entire apparatus is again in a condition to respond to the critical pressure.

1. In a control switch, a stationary cont-act, an oscillatable arm, a contact carried by the arm coacting with the stationary Contact, an electromagnet, an armature for the magnet, said armature being coaxially pivoted with the arm, a resilient connection between the armature and the arm, said contacts being arranged to short circuit the electromagnet, means for locking the armature inits attracted position at its free end andI a Weight carried bythe armature at its free end for causing it to continue to travel with appreciable momentum after the electromagnet is shortcircuited.

2. In a control switch, contacts, a pressure cell for operating the contacts to perform a switching operation in response to a criticalA for varying the pressure in the cell in a direclaoA tion opposed to that necessarily to cause the reverse switching operation.

3. y In a control switch, contacts, a pressure cellfor operating the contacts to perform a f switching operation in response to a critical operating the' main contacts to perform a pressure, means for performing the reverse switching operation, and means for increasing the pressure in thescell active only after the pressure cell has operated the contacts and before the latter means has operated them in the reverse direction.

4. In Aa control switch, main contacts, a

pressure cell having a movable diaphragm for switchingfunction, when the pressure inthe cell reaches a critical value, a circuit including a heating element within the cell adapted to be energized when the contacts are operated by the cell, whereby vthe pressure in the cell is increased, and means for returning the contacts to the original position in response to the receding of the pressure from the criti-` cal value.

5. In a control' switch, an electromagnet adapted to be energized from an electrical circuit, a movable armature for said electromagnet, movable and stationary contacts connected to said electrical circuit whereby said electromagnet is deenergized upon closing of said contacts, a movable member to which one of said contacts is fixed, resilient means connecting said armature and said member, latch means for retaining said armature in closed position whereby said contacts are g pressed together by said resilient means, and

a weight carried by the armature whereby inertia of the armature serves to cause continued movement of the same after closing of the cont-acts. y

6. In a switching device, a pair of relatively movable contacts, an eXpansible pressure cell containing an expansible Huid, an electrical heating element serving to supply heat to said fluid, mechanical means interconnecting said cell and contacts whereby expansion of said cell effects a. switchingoperation, and means for eifecting energization of said element during a switching operation.

In testimony whereof, I have hereunto set my hand.l

ARTHUR J. KERCHER. 

